Meyer R., Koehler J., Homburg A. Explosives. Wiley-VCH, 2002 / Explosives 5th ed by Koehler, Meyer, and Homburg (2002)

Armstrong Blasting Process	22

solid targets. The explosive is charged into the test projectile and is fired from a “gun” against a steel plate. The impact velocity which causes the charge to detonate is determined. The test description:

W Susan Test.

Armstrong Blasting Process

This is an extraction method in the USA in coal mining. The highly Compressed (700 – 800 atm) air in the borehole is suddenly released by means of so-called blasting tubes equipped with bursting discs. The compressed air is generated underground by special compressors (W also Gas Generators).

A similar method has received the name Airdox. The bursting elements in the blasting tubes have a different construction; the compressed air utilized in the method can be generated overground and distributed over a network of ducts.

ARRADCOM

US Army Armament Research and Development Command; Picatinny Arsenal Dover, New Jersey, USA

Center for research, development, approval and documentation on weapons and military materials.

Audibert Tube

Audibert-Rohr

This testing apparatus, which was first proposed by Audibert and Delmas, measures the tendency to W Deflagration of a permitted explosive. A cartridge containing the test sample is placed, with its front face open, in the tube and is packed tightly on all sides with coal dust. An incandescent spiral is placed in the cartridge opening; if the material is difficult to ignite (e.g. inverse salt-pair permissibles) the spiral is covered with a flammable igniter mixture. The tube is then closed by a perforated plate. The parameter measured is the minimum hole diameter at which the initiated deflagration arrives at the bottom of the cartridge.

In a modification of the method two cartridges placed coaxially one an top of the other are tested.

23	Ballistic Bomb

Aurol

T-Stoff, Ingolin

Concentrated (88 – 86 %) hydrogen peroxide. It is employed in liquid fuel rocket engines as W Oxidizer or, after catalytic decomposition, as W Monergol. For its explosive properties, see Haeuseler, Explosivstoffe 1, pp. 6 – 68 (1953).

AUSTROGEL G1

AUSTROGEL G1 is a safe-to-handle, cap-sensitive gelatinous ammonium nitrate explosive. This successor explosive replacing W Gelatine Donarit 1 does not contain any nitro-aromatics harmful to health such as W Dinitrotoluene and W Trinitrotoluene, and is manufactured by the DYNAMIT NOBEL Wien Company.

Average Burning Rate*)

Mittlere Abbrandgeschwindigkeit; vitesse moyenne de combustion

The arithmetic mean (statistical average) burning rate of pyrotechnic or propellants at specific pressures and temperatures. Dimension – length/time or mass/time.

Azides

Azide; azotures

Azides are salts of hydrazoic acid (N3H). Alkali metal azides are the most important intermediates in the production of W Lead Azide.

Sodium azide is formed by the reaction between sodium amide (NaNH2) and nitrous oxide (N2O). Sodium amide is prepared by introducing gaseous ammonia into molten sodium.

Ballistic Bomb

closed vessel, ballistische Bombe, bombe pour essais ballistiques (W Burning Rate)

The ballistic bomb (pressure bomb, manometric bomb) is used to study the burn-up properties of a W Gunpowder or W Propellant charge powder. It consists of a pressure-resistant (dynamic loading up to about 1000 MPa (10 000 bar) hollow steel body that can be bolted

* Text quoted from glossary.

	, Fifth Edition Rudolf Meyer, Josef Köhler, Axel Homburg
23

Aurol

T-Stoff, Ingolin

Concentrated (88 – 86 %) hydrogen peroxide. It is employed in liquid fuel rocket engines as W Oxidizer or, after catalytic decomposition, as W Monergol. For its explosive properties, see Haeuseler, Explosivstoffe 1, pp. 6 – 68 (1953).

AUSTROGEL G1

AUSTROGEL G1 is a safe-to-handle, cap-sensitive gelatinous ammonium nitrate explosive. This successor explosive replacing W Gelatine Donarit 1 does not contain any nitro-aromatics harmful to health such as W Dinitrotoluene and W Trinitrotoluene, and is manufactured by the DYNAMIT NOBEL Wien Company.

Average Burning Rate*)

Mittlere Abbrandgeschwindigkeit; vitesse moyenne de combustion

The arithmetic mean (statistical average) burning rate of pyrotechnic or propellants at specific pressures and temperatures. Dimension – length/time or mass/time.

Azides

Azide; azotures

Azides are salts of hydrazoic acid (N3H). Alkali metal azides are the most important intermediates in the production of W Lead Azide.

Sodium azide is formed by the reaction between sodium amide (NaNH2) and nitrous oxide (N2O). Sodium amide is prepared by introducing gaseous ammonia into molten sodium.

Ballistic Bomb

closed vessel, ballistische Bombe, bombe pour essais ballistiques (W Burning Rate)

The ballistic bomb (pressure bomb, manometric bomb) is used to study the burn-up properties of a W Gunpowder or W Propellant charge powder. It consists of a pressure-resistant (dynamic loading up to about 1000 MPa (10 000 bar) hollow steel body that can be bolted

* Text quoted from glossary.

Ballistic Bomb	24

together and has a hole to accommodate a piezoelectric pressure transducer. The pressure p in the bomb is measured as a function of time t.

As a rule, studies of powder in the pressure bomb are carried out in comparison with a powder of known ballistic performance. They are very useful both in the development of powders and in production monitoring.

If the dynamic liveliness L (= 1/pmax * dlnp/dt) is determined as a function of p/pmax from the primary measured signal, then for a defined powder geometry the parameters characterising its burn-up, the linear burning rate e˙ (W Burning Rate) and the pressure exponent a can be determined. Pressure bomb shots of the same powder at different charge densities d (= mass mc of powder/volume VB of the pressure vessel) enable the specific covolume h of the combustion gases from the powder and the force f (powder force) of the powder to be determined in addition. From these, if the W Heat of Explosion QEx of the powder is known, the value of the average adiabatic coefficient æ (= 1 + f/QEx) of the combustion gases, which is of interest for the ballistic performance, can be derived.

Since the combustion gases of powders satisfy Abel’s equation of state to a good approximation, it is possible by using the auxiliary parameters (rc) density of the powder)

D : = mc/(VB * rc)	‘normalised charge density’	(1)
x : = (1 – hrc) * D/(1 – D)	‘real gas correction term’	(2)
F : = frcD/(1 – D)	‘characteristic pressure’	(3)

to write the relationship between the pressure p in the manometric bomb and the burnt volume proportion z of the powder as

z(p/pmax) = p/pmax/{1 + x(1 – p/pmax)}	(4)
and
p(z) = F * z / (1 + xz).	(5)

Accordingly, the maximum gas pressure achieved at the end of burnup (z = 1) is calculated as

pmax = F / (1 + x).											(6)
The dynamic liveliness L is calculated from
S(0)	e˙(pref)	* [	p	]	a–1		1	+	x
L = V(0) * f(z) *						*					(7)
	pref		pref				(1	+	xz)2

S(0)/V(0) is the ratio of the initial surface area to the initial volume of the powder,

f(z) is the shape function of the powder, which takes account of the geometrical conditions (sphere, flake, cylinder, N-hole

25	Ballistic Bomb
	powder) during the burn-up (f(z) = current surface area /
	initial surface area)
e˙(pref)	is the linear burning rate at the reference gas pressure pref
pref	is the reference gas pressure and

ais the pressure exponent, which for many powders is close to 1.

To evaluate Eq. (7), z should be replaced by p/pmax using Eq. (4). Figure 3 shows the time profile of the pressure in the manometric bomb for a typical 7-hole powder. Initially the pressure is increasingly steep, since burn-up takes place more quickly the higher the pressure

Fig. 3. Pressure-time graph p = f(t)

Fig. 4. Dynamic liveliness as a function of p/pmax

Ballistic Mortar	26

Fig. 5. Shape function pf the powder as a function of the current surface area relative to the initial surface area

and in addition the burning surface of the powder becomes greater as the burn-up progresses (progressive burn-up). Towards the end of the burn-up the pressure profile levels out rapidly because the burning surface area of the powder becomes drastically smaller as soon as approx. 88 % of the powder has been burnt.

Figure 4, which shows the calculated profile of the dynamic liveliness as a function of p/pmax, again reflects essentially the shape of the form function for p/pmax > 0.2 (see Fig. 5). On the other hand for small values of p/pmax, the dependence on pa-1 resulting for a = 0.9 is dominant. The kink in the shapes of the form function and the dynamic liveliness at p/pmax = 0.87 (disintegration of the powder granules into slivers) is greatly rounded off in the measured curves, because not all of the granules burn up at exactly the same time and small differences in geometry always arise (manufacturing tolerances)

Ballistic Mortar

ballistischer Mörser, mortier ballistique

An instrument for comparative determinations of the performance of different explosives. A mortar, provided with a borehole, into which a snugly fitting solid steel projectile has been inserted, is suspended at the end of a 10 lt long pendulum rod. Ten grams of the explosive to be tested are detonated in the combustion chamber. The projectile is driven out of the mortar by the fumes, and the recoil of the mortar is a measure of the energy of the projectile; the magnitude determined is the deflection of the pendulum. This deflection, which is also known as

27	Ballistic Mortar

weight strength, is expressed as a percentage of the deflection produced by blasting gelatine, arbitrarily taken as 100. Also, relative values referring to the deflection produced by TNT are listed, especially for explosives of military interest.

Fig. 6. Ballistic mortar.

This method, which is commonly employed in English-speaking countries, and which is suited for the experimental determination of the work performed by the explosive, has now been included in the list of standard tests recommended by the European Commission for the Standardization of Explosive Testing.

An older comparison scale is “grade strength”, which determines the particular explosive in standard “straight” dynamite mixtures (the mixtures contain ungelatinized nitroglycerine in different proportions, sodium nitrate and wood or vegetable meal (W Dynamites) which gives a pendulum deflection equal to that given by the test material. The percentage of nitroglycerine contained in the comparitive explosive is reported as grade strength.

The grade strength percentage is not a linear indicator of the performance of the explosive; the performance of a 30 % dynamite is more than half of the performance of a 60 % dynamite, because the fueloxidizer mixtures as well as nitroglycerine also contribute to the gasand heat-generating explosive reaction.

Ball Powder	28

For comparison of weight strength values with other performance tests and calculations W Strength.

Ball Powder

Kugelpulver, Globularpulver; poudre sph´erique

Ball powder is a propellant with ball-shaped particles, produced by a special method developed by Mathieson (USA). A concentrated solution of nitrocellulose in a solvent which is immiscible with water (e.g., ethyl acetate) is suspended in water by careful stirring, so that floating spheres are formed. The solution is warmed at a temperature below the boiling point of the solvent, and the latter gradually evaporates and the floating spheres solidify.

Since the spherical shape is unfavorable from internal ballistical considerations (very degressive), follows, a thorough W Surface Treatment, the purpose of which is to sheathe the faster-burning core by a slower-burning shell.

BAM

Bundesanstalt für Materialforschung und -prüfung

D-12200 Berlin

Federal Institute for Materials Research and Testing (including explosives). BAM sensitivity tests: W Friction Sensitivity W Heat Sensitivity and W Impact Sensitivity.

Baratols

Pourable TNT mixtures with 10 – 20 % barium nitrate.

Barium Chlorate

Bariumchlorat; chlorate de barium

Ba(ClO3)2 · H2O

colorless crystals molecular weight: 322.3

energy of formation: – 789.3 kcal/kg = – 3302.3 kJ/kg enthalpy of formation: – 799.4 kcal/kg = – 3344.6 kJ/kg oxygen balance: +29.8 %

density: 3.18 g/cm3

melting point: 414 °C = 779°F

29	Barricade

Barium chlorate and W Barium Perchlorate are used in pyrotechnical mixtures using green flames.

Barium Nitrate

Bariumnitrat; nitrate de barium: BN

Ba(NO3)2

colorless crystals molecular weight: 261.4

energy of formation: – 898.2 kcal/kg = – 3758.1 kJ/kg enthalpy of formation: – 907.3 kcal/kg = – 3796.1 kJ/kg oxygen balance: +30.6 %

nitrogen content: 10.72 % density: 3.24 g/cm3

melting point: 592 °C = 1098°F

component in green flame pyrotechnicals and in ignition mixtures (with

W Lead Styphnate).

Barium Perchlorate

Bariumperchlorat; perchlorate de barium

Ba(ClO4)2 · 3H2O

colorless crystals molecular weight: 390.3 oxygen balance: +32.8 % density: 2.74 g/cm3

melting point: 505 °C = 941°F

An oxidizer in propellant formulations and for W Pyrotechnical Compositions.

Barricade

Schutzwall; merlon, ecran´

Barricades are grown-over earth embankments erected for the protection of buildings which may be endangered by an explosion. The overgrown height of the barricade must be at least one meter above the building to be protected. The required safety distances between explosive manufacture buildings or storage houses can be halved if the houses are barricaded.

Table 1. Specifications

	Class	Class	Class	Class	Class	Class
	1	2	3	4	5	6
net content by nitrogen analysis:
at least	99.7 %	99.0 %	99.5 %	99.5 %	98.5 %	99.5 %
Sr: not more than	0.6 %	–	0.6 %	–	–	0.6 %
Ca: not more than	0.05 %	–	0.05 %	–	–	0.05 %
Al2O3 + Fe2O3: not more than	–	0.50 %	–	–	–	–
Na, as Na2O: not more than		0.15				0.15
Chloride, as BaCl2, not more than	0.0075 %	0.0075 %	0.0075 %	0.0075 %	–	0.0075 %
grit: not more than	0.05 %	0.05 %	0.05 %	0.05 %	–	0.05 %
Fe and other metals	none	none	none	none	none	none
moisture: not more than	0.20 %	0.10 %	0.20 %	0.20 %	0.05 %	0.10 %
pH:	5.0 – 8.0	5.0 – 8.0	5.0 – 8.0	–	5.0 – 8.0	5.0 – 9.0
insoluble matter: not more than	0.1 %	0.1 %	0.1 %	0.1 %	0.1 %	0.1 %

Nitrate Barium

30